1. Field of the Invention
The present invention relates to a rotary hook, more particularly to a construction wherein an inner bobbin case is supported by a rotary outer loop taker with a flange-like track projection formed on the bobbin case being fitted into a track groove fromed in the loop taker.
2. Description of the Prior Art
In a rotary hook wherein an outer loop taker is driven for rotation with a flange-like track projection formed on an inner bobbin case fitting into a track groove formed in the loop taker and the bobbin case is stopped from rotating, the loop taker cannot be rotated at an exceedingly high speed due to friction between the track groove and the track projection. Hence there is a limit to making improvements in the sewing performance. Conventionally it has been proposed to supply lubricant oil between the track groove and the track projection so as to reduce frictional resistance produced therebetween. In such prior art arrangement, however, the thread tends to be soiled by the lubricant oil thus employed. The sewing operation cannot therefore be executed smoothly.